Choosing a Valley Detail for the Actual Shingle
Bulletin revision: February 1, 2021
Open, closed-cut and woven valleys are not interchangeable for every product. GAF distinguishes acceptable details by shingle type, slope and warranty conditions.
GAF technical bulletin: Valley flashing options.
What this means for your roof
Open, closed-cut and woven valleys are not interchangeable for every product. GAF distinguishes acceptable details by shingle type, slope and warranty conditions.
A useful question for your contractor
Ask which valley detail is specified and where fasteners must stay clear of water flow.
Ask for the answer to be tied to the actual roof condition and the exact product being installed. Keep the agreed repair or installation detail with your estimate and project photos.
Bulletin revision: February 1, 2021. This is the date of the manufacturer source, not a claim that this website guide existed on that date.
Read GAF: Valley flashing options
This homeowner summary explains the cited bulletin. The complete manufacturer document and current product instructions govern the installation details. A requirement for one manufacturer or product should not be transferred to another without checking.